Overnight, Ike flooded Galveston's historic district and left all of Galveston County without power, the Galveston County Office of Emergency Management reported on its Web site. Four million people in Houston also lost power.

Officials have blamed Ike for three deaths. All 22 people aboard a Cypriot freighter that was caught in the storm off the coast of Texas were safe, however, according to the Coast Guard, which had earlier abandoned efforts to rescue the crew because of Ike.

The hurricane is expected to move through eastern and northeastern Texas today, weakening as it travels inland, and then into western Arkansas tonight, the Hurricane Center said. Its projected track will take it over Missouri, Illinois, Indiana, and then Ohio before hitting Canada late Sunday.

For more on what causes hurricanes, and how they are linked to global warming, see our in-depth report.